A friend of mine used to always say "expectations lead to disappointments" and she is completely right. Everyone has standards and not everyone or everything will meet them. You have to understand that, sometimes, if the people around you continually disappoint you, its not because they're incompetent but because you set the bar too high for them. Even if you want to have high expectations or set large goals, don't just assume that everyone can reach them. Everyone wants different things in life, everyone has different priorities.
If you go though life with many expectations, you must also expect disappointments. They pretty much come hand in hand. But disappointments are not the end of the world. They don't mean that you should give up on what you want. They are simply a way of telling you to aim lower and work your way up. One day the people and things around you will meet your standards and when that day comes, maybe you can expect a little more. Maybe*.
*I believe that the thing that will lessen the disappointments in life is the word "maybe." Its like saying "maybe it will happen and maybe it won't. You never know for sure."